Refrigeration system



May' 16, 1939.

J. R. CHAMBERLAIN REFRIGERATION SYSTEM Filed Nov. 2'7, 1957 (IttornegsPatented May 16, 1939 .UNITED STATES REFRIGERATION SYSTEM Joseph R.Chamberlain,

York, Pa.; assignor to- York Ice Machinery Corporation, York, Pa., acorporation of Delaware Application November 27, 1937, SerialNo.'178,866

Claims.

This invention relates to refrigeration systems and particularly tosystems of the compressorcondenser-expander type.

In refrigerating systems of this type and par- 6 ticularly as applied tocommercial installations, it is; common practice for reasons ofefficiency and convenience to locate the compressor unit in the basementof a building to be refrigerated, and the condensing unit on the roof orat some other 4 elevated point where unobstructed air simulation can beobtained. The condensers frequently take the form of a coolingtower-condenser in which water is continuously showered over thecondenser coil, preferably countercurrent to the circulation of air oversuch coil. Installations of this kind are subject to protracted standbyperiods over week ends or holidays when the apparatus remains idle. Thecondenser unit and the compressor unit are subject to the widelydifferent temperatures of a relatively cool basement and the relatively,warm outside air. When'the system .is idle, especially in warm weather,the vapor pressure of refrigerant in the condenser will be substantiallygreater than the vapor pressure of refrigerant in the discharge lineleading from the compressor to the condenser, since there is freecommunication between them. Evaporation willtend to occur in thecondenser or condensation will tend to occur in the discharge lineadjacent the compressor. If the condition persists long enough, theliquid in the receiver will evaporate and the vapor will flow backwardsthrough the condenser unit and ultimately condense in the dischargeline. and find its way to the compressor.

The object of the present invention is to so modify existing apparatusthat condensed refrigerant'can never reach the compressor, and toaccomplish this by providing a liquid sump in the line between thecondenser and the compressor, and of suflicient' capacity to receive andhold all .refrigerantwhich can ever condense in this lineunder anyconditions. It is further proposed to so locate therefrigerant sump thatwhen the sys- {5 tem is'restarted after a shut-down, it will resume itsnormal operation quickly and safely, and will continue to operate as itwould if the safety sump werenot present. I .Other. objects will beapparent from the specification. I ln th'e drawing the single figureis-a diagrammatic view 9f one form of apparatus embodying the presentinvention, and showing the construction-of the compressor and itsassociated refrig- 55 erant'sump v r Referring to the drawing, referencecharacter 5 designates the outline of a building having a compressorunit C located in the basement, a condenser unit D located on the roof,and an evaporator unit E inside of the building, the 5 ground line beingindicated at G. The compressor unit comprises the usual. base 6 having,mounted thereon a compressor 1 and a driving motor 8. The base alsohouses a tank or refrigerant sump 22. The-condenser unit comprises an 1enclosing casing 9 containing a condenser coil ll associated with aliquid receiver l2, and a water circulating pump l3 for showeringcooling water from pipe l4 over the coil. This unit pref:

erablyincludes an air circulating fan having an outlet l5 wherebyevaporation of the cooling wa 'ter is increased, and the cooling effectof the condenser is thus enhanced. The receiver l2 is connectedby pipe I6 to the evaporator E through an expansion valve H, which may becontrolled by a heat sensitive bulb l8 associated with the line I9connecting the outflowend of the evaporator E to the low pressure sideof the compressor.

In the usual construction of systems of this type, the high pressureside of compressor 1 would be connected directly to the topside of thecondenser coil H so as to convey hot compressed gas directly from thecompressor to the condensrer. In the present instance, however, the pipe2| leading from the high pressure side of the compressor passes to therefrigerant sump 22 having at its bottom an offtake pipe 23 connected tothe intake of condenser coil II. The sump 22 has a capacity sufljcientto hold the volume of refrigerant which may, under any conditions,condense between the compressor and condenser. Use of' a compressor unitin this way simplifies the apparatus and makes it possibleto use asingle type of compressor unit interchangeably either in a system of thepresent type, where tank 22 serves as a refrigerant sump, or in arefrigeratingsystem .where this tank serves as a refrigerant condenserand receiver. The normal operation of the system is the same as that ofusual practice. Briefly stated, evaporated refrigerant coming from theevaporator E to the intake of compressor I, is compressed and passesthrough pipe 2|, sump 22 and line 23 to condenser- II, where it comesinto heat exchanging relation through the walls of the condenser coilwith the relatively cool water flowing 'over this coil and with the airwhich is circulating over thiscoil. As the gas passes downwardly throughthe coil toward the receiver I2, .it' gradually loses heat until itliquefies and collects in the receiver l2, whence it flows through pipel6 and expansion valve I! to evaporator E in liquid form. The expansionvalve I1 is shown as of the automatic or thermally controlled type, inwhich a thermostatic bulb IB regulates the expansion valve inconjunction with the pressure and temperature on the discharge side ofthe valve. The thermostatic bulb being placed on the suction line IS,the valve operates to insure that the refrigerant is slightlysuperheated in the suction line, a con-- dition which guards against theflow of liquid refrigerant from the evaporator to the compressor.However, the invention is not limited to any particular type ofexpansion valve, and other conventional mechanisms, such as,particularly, low side float valves, might be used exactly as they areused in current practice. v

The operation just described is standard practice in refrigerationsystems of the type to which this invention relates. The operation ofsuch systems, so long as there are no standby periods. is thoroughlysatisfactory with known types of structure and without the interpositionof the refrigerant sump 22. When, however, the apparatus is shut downfor comparatively long periods, the widely different temperatureconditions existing at the condenser coil II and in the basement wherethe compressor 1 is located, cause a great difference in vapor pressurebetween the compressor and the condenser. When the apparatus shutsdownfsome liquid refrigerant willalways be present in the receiver l2where it becomes subject to gradually increasing temperature andvaporizes as the temperature of the condenser coil H rises, since thereis no circulation of cooling water within the casing 9. While thetemperature of the condenser coil H rising, the temperature Within thecool basement remains substantially the same, so that the vapor pressuredifferential at the two ends of pipe'23 eventually increases to thepoint where refrigerant condenses in the line and collects in the sump22.

During operation of the system the compressor, as well as the sump anddischarge line, become relatively hot. The compressor is composed of acomparatively heavy mass of metal whereas the sump and discharge lineare made of lighter and thinner metal having less heat storing capacitythan the compressor. Consequently, when the system is shut down andcools off, the sump and discharge line cool to ambient temperature muchmore quickly than the compressor. When, therefore, condensate starts toflow back through'the discharge line from the condenser, before theentire system has had time to cool down, it will go to the coldest pointin the system, namely to the sump, and will remain there in liquid formwithout any tendency to pass to the warmer compressor. In this way it isassured that the condensed refrigerant will collect in the sump and notin the compressor.

This condensation may continue until the entire volume of refrigerantpresent between expansion valve H on the condenser side, line l6,receiver 12, condenser coil II and line 23, i. e., in the high side ofthe system, has condensed and collected in the sump 22. Forabsolutesafety it is preferred to make this sump of a volume sufficientto hold the entire charge of liquid refrigerant in the system, but theessential requirement is that it be large enough tohold all liquid whichcould condense under the most extreme condition to which the systemcould ever be subject. In most systems, and with a sufficientlyprotracted standby period under the conditions noted, this liquid volumemight approximate the entire charge. Consequently, with the arrangementillustrated, there can never be any danger of the compressor head beingblown off by reason of its starting up with liquid refrigerant present'in the cylinder. The operation of the sump 22 is effective regardlessof the length of standby periods, and it is immaterial whether theentire volume or only a part of the refrigerant condenses therein.

When the system is started up, after a standby period in which liquidhas collected in the sump 22, the compressorstarts immediately tocompress the gas coming from line l9, and to force it under pressureinto the sump 22, where it displaces the condensed refrigerant liquidinthe sump, and sends it through the line 23 to the condenser II. All ofthe liquid in sump 22 is displaced before any gaseous refrigerant canflow from the compressor to the condenser. Refrigeration is obtainablealmost immediately after the compressor starts, because the condensedrefrigerant is sent to the evaporator quickly.

In the example given, the refrigerant sump 22 has been illustrated aslocated in the compressor base for reasons of convenience, although itwill be understood that it may be placed in otherlocations and stillbring about the result which is here obtained. The essential point isthat the sump be of a capacity, and be so located in the line betweenthe off-take of the compressor and the inlet of the condenser, that nocondensed refrigerant can ever reach the compressor under any conditionsto which the system may be subjected.

- The system shown herein is merely by way of illustration as it isobvious that the inventive concept may be applied to other known typesof system where, as a result of temperature differences between thecompressor and condenser units, this-problem of refrigerant condensationduring standby periods may appear.

I claim:

1. In a refrigeration system, a compressor for gaseous refrigerant: anevaporator; a condenser connected between the compressor and saidevaporator for condensing the gaseous refrigerant and supplying it tosaid evaporator in the form of a liquid, said condenser being subject toa temperature differing substantially from that of the compressor; and arefrigerant sump subject to substantially the same ambient temperatureas the compressor, interposed in the high pressure side of the systembetween said compressor and condenser for receiving. refrigerantcondensed from the system during standby periods and preventing it fromreaching the compressor.

2. The combination with a refrigerating circuit including a compressor,a condenser, and an evaporator, of a liquid trap connected between thecompressor and the condenser, said trap being subject to an ambienttemperature substantially different from that of said condenser butapproximating that of said compressor and so arranged that refrigeranttending to flow in vapor form from the condenser and to condenseadjacent the compressor during standby periods, will be collected insaid trap and displaced therefrom to the condenser, by pressuredeveloped as an incident to the resumption of operation of thecompressor.

3. In a refrigeration system, a compressor for gaseous refrigerant; anevaporator; a condenser connected between the compressor and evaporatorfor condensing the gaseous refrigerant and supplying it to theevaporator in liquid form, said condenser being located at a differentlevel from that of the compressor and being subject to a temperaturediffering materially from that of the compressor; and a liquid trapconnected between the compressor and the condenser, said.

trap being so arranged that refrigerant tending to flow in vapor formfrom the condenser so as to condense adjacent the compressor duringstandby periods, will be collected in said trap and be displacedtherefrom to the condenser by pressure developed as an incident to theresumption of operation of the compressor at the conclusion of a standbyperiod.

4. In a refrigeration system, a compressor unit comprising a hollow basehaving a tank disposed therein; a compressor mounted on said base; amotor mounted on said base and operatively connected to drive saidcompressor; a condenser unit located at a point remote from saidcompressor and subject to a substantially different ambient temperaturethan that of the compressor; an

evaporator connected between the condenser and the suction side of thecompressor; and means for connecting said tank in circuit between saidcondenser and the high pressure side of said compressor to causerefrigerant tending to flow in vapor form from the condenser and tocondense adjacent the compressor during standby periods, to be collectedin said tank and displaced therefrom to the condenser by pressuredeveloped as an incident to the resumption of operation of thecompressor after a standby period sufiicient to cause condensation ofrefrigerant in said tank.

5. The combination with a refrigerating circuit including a compressor,a condenser and an evaporator, of a liquid trap connected between thecompressor and condenser and subject to ambient temperature conditionsapproximating those of said compressor, but difiering substantially fromthose of said condenser, said trap having less heat storing capacitythan the com pressor,-and being so arranged that refrigerant tending toflow in vapor form from the condenser and to condense adjacent thecompressor during standby periods will collect in said trap.

JOSEPH R. CHAMBERLAIN.

